LISFLOOD-FP

LISFLOOD-FP, developed at the University of Bristol since the late 1990s, pioneered computationally cheap raster-based floodplain inundation using the local inertial approximation of the shallow-water equations. It is the engine behind much of the global flood-hazard mapping industry, having scaled to continental and global runs long before commercial engines did.

Now open source, version 8 adds DG2 (second-order discontinuous Galerkin) and GPU solvers. It suits research, large-domain screening and global hazard work; for structure-heavy design studies a full-featured engine like HEC-RAS or TUFLOW remains more practical.